The invention relates to valve blocks and valve assemblies and particularly to valve blocks and pneumatic valves for controlling the operation of a glassware forming machine for manufacturing glass containers and more specifically to an I.S. (individual section) machine such as disclosed in U.S. Pat. No. 5,803,945. Modem glass container forming machines of the type IS (independent section), are controlled by controllers of various manufacture. One such pneumatic machine control unit is shown in U.S. Pat. No. 6,269,662. That patent describes an I.S. machine having at least one machine section for processing a gob of molten glass into a selected bottle. The section is supplied by a plurality of pneumatic lines at different pressures. A pneumatic supply input line supplies a manifold which is connected to a plurality of output lines. The interface between the controller and the I.S. section is a valve block assembly that usually includes twenty one independent valves.
An I.S. machine is made up of a number (8, 10, 12, . . . ) of identical sections each of which receives a gob of molten glass and forms the gob into a bottle. The bottle is formed in a two step process. The gob is received by a blank mold at a blank station and is formed into a parison having a threaded opening at the bottom (the finish). The blank station includes apposed pairs a of blankmold halves and the blow station includes apposed pairs of blowmold halves. Each of these mold halves is carried on an insert which is mounted on an arm or support which is displaceable between open and closed positions.
The parison is transferred by an invert/neck ring mechanism to the blow molds at a blow station which receives the parisons and forms them into bottles. Operating air is supplied to each section to operate individual section mechanisms. “High pressure” and “low pressure” air are required. When the two step process is the “press and blow” process, a plunger is advanced into the gob within the blank mold to form the parison with “plunger up air”. Bottle making air is also required. Where the two step process is the “blow and blow” process “settle blow” air is required to settle the molten glass around the plunger. Additionally “final blow”, “finish cooling”, and “counter blow” air may be required. In addition, air may be required for associated section mechanisms such as the pushout (see U.S. Pat. No. 5,527,372 which uses pressurized air at the pockets (“pocket air”). These pneumatic services are channeled from a main supply into a plurality of manifolds that are located on or about the machine. Each manifold requires a pressure regulating device so that the pressure may be controlled as required for each function. In state of the art machines, each pressure regulating device is a part of the individual pneumatic service and is located to be convenient to that pneumatic service. As a result the regulating devices are scattered about the machine and each is individually settable by the operator.
The prior art valve blocks include the apparatus shown in U.S. Pat. No. 3,918,489 entitled “Valve Block” issued on Nov. 11, 1975; U.S. Pat. No. 4,100,937 entitled Valve Block issued on Jul. 18, 1978; U.S. Pat. No. 5,582,209 entitled “Valve Block Assembly” for I.S. machine issued on Dec. 10, 1996; and U.S. Pat. No. 6,142,185 entitled “Valve Block” issued on Nov. 7, 2000. The valve block shown in U.S. Pat. No. 3,918,489 is representative of typical prior art valve blocks. The apparatus includes twenty-one valve assemblies which each include a pilot-operated poppet valve controlled by a pilot air directed to the poppet valve by a solenoid-operated pilot valve. The twenty-one valve combinations are arranged in two rows. The apparatus includes separate cast blocks in which respectively a set of pilot valves and a set of set of poppet valves are disposed.
The prior art valve blocks have not been wholly satisfactory. The machines for manufacturing glassware require an extremely high capital investment. Accordingly, it is highly desirable to maximize the time the machine operates. Ideally the machines will operate at maximum capacity twenty four hours a day and seven days a week. Thus, ideally each pilot-operated poppet valve and each solenoid-operated pilot valve will accordingly operate approximately fourteen duty cycles per minute for each minute in each hour in each day of each year. Therefore, each of the twenty one poppet valves, each of the twenty one pilot valves and each of the twenty one solenoids in the prior apparatus will ideally function flawlessly at all times.
Even with the most careful design engineering and quality control this is not possible. In addition the construction of the prior art apparatus makes it difficult to access the poppet valves and pilot valves. The poppet valves are mounted in one block and the pilot valves are mounted in another block. A check of solenoid operation, for example, requires removal of a complete front cover containing switches, lamps and cables. Changing a poppet or pilot valve requires complete removal of the entire front cover, wiring harness and the solenoid block from the rest of the valve block assembly. The complications inherent in inspecting, testing and replacing these components increase the time required for maintenance resulting in downtime for the machine and less production from the capital intensive machine. In addition, the prior art valve block assembly constrains air flow to pilot and poppet valves which can affect the speed and precision of the I.S. machine operation.
The design of alternative valve block assemblies is complicated by the somewhat conflicting design constraints of extremely high reliability and limited available space imposed by the glassware manufacturing machine structure.